The RRAF map is based on a National Weather Service model used for flood forecasting. This model takes into account soil moisture content, forecast precipitation and temperatures, snow accumulation and melt to predict the likelihood of daily, next day, and 72 hour runoff events.
There was a relatively high amount of uncertainty for some precipitation forecasts more than five days out. The three-day composite runoff risk provides relatively conservative estimate of runoff risk while maintaining a better degree of accuracy in forecasting. It is also trying to alert producers of upcoming risk more than a day out to help with planning purposes. This can be especially important for surface applications that might rest on top of the soil and be susceptible.